Coal in its virgin state is sometimes treated to improve its usefulness and thermal energy content. The treatment can include drying the coal and subjecting the coal to a pyrolysis process to drive off low boiling point organic compounds and heavier organic compounds. This thermal treatment of coal, also known as low temperature coal carbonization, causes the release of certain volatile hydrocarbon compounds having value for further refinement into liquid fuels and other coal-derived liquids (CDLs) and chemicals. Subsequently, the volatile components can be removed from the effluent or gases exiting the pyrolysis process. Such thermal or pyrolytic treatment of coal causes it to be transformed into coal char by virtue of the evolution of the coal volatiles and products of organic sulfur decomposition. The magnetic susceptibilities of inorganic sulfur and iron in the resultant char are initiated for subsequent removal of such undesirable components as coal ash, inorganic sulfur and mercury from the coal char.
It would be advantageous if agglomerating or bituminous coal could be treated in such a manner that would enable volatile components to be effectively removed from the coal at more desirable concentrations, thereby creating a coal char product having reduced organic sulfur and mercury. It would be further advantageous if bituminous coal could be refined in such a manner to create a second revenue stream (i.e., condensable coal liquids), which could be recovered to produce syncrude and other valuable coal products.
For example, even CDLs collected and separated may contain undesirable particulate matter—as much as 5-10% by weight by some estimates. These small, micron-sized particulates are generally undesirable, particularly if the CDL is to be further processed or refined by additional equipment. Therefore it would be advantageous to remove significant portions of these fine particulates.